Electronic Components: Resistors PDF

I. Electronic component. Electronics is the branch of science and engineering that deals with the study, design, and application of devices, circuits, and systems that control the flow of electrons or other electrically charged particles. An electronic component is a basic element used...

I. Electronic component. Electronics is the branch of science and engineering that deals with the study, design, and application of devices, circuits, and systems that control the flow of electrons or other electrically charged particles. An electronic component is a basic element used in electrical circuits to control, manipulate, or generate electrical energy or signals. These components can either be passive or active. I.1. Passive components. A passive element is an electrical component that does not generate power, but instead dissipates, stores, and/or releases it. Passive elements include: I.1.1. Resistor: made of copper wires which are coiled around a ceramic rod and the outer part of the resistor is coated with an insulating paint. The main purpose of resistor is to reduce the current flow and in any particular portion of the circuit. The SI unit of resistor is Ohm ().  Resistor types: There are different types of resistors, which are mainly classified into (figure 1): a- Linear Resistors. In Linear Resistors, the value of resistance changes based on the applied temperature and voltage. These Linear Resistors are again classified into Fixed and Variable Resistors. a.1. Fixed Resistors: In Fixed Resistors, the value of resistance is fixed and cannot be changed. These are mostly used in fixed circuits because the resistance value is fixed. Fixed Resistors are mainly used in electronic circuits where a stable or fixed resistance is required, For example: in voltage dividers or current limiters. Fixed Resistor follows Ohm’s law, which states, that voltage (V) is directly proportional to current (I) and resistance (R). There are different types of Fixed Resistors: -Carbon Film Resistor. 1  -Wire Wound Resistor. -Metal Film Resistor. a.2. Variable Resistors: In Variable Resistors, the value is not specific and can be changed and can manually adjust the value of resistance by using the dial, knob of a screw. It is also known as potentiometer having two connecting wires instead of three. Variable Resistors are mainly used in applications where resistance needs to be variable, for example: in volume controls or sensor applications or radio receiver. There are the different types of Variable Resistors: -Potentiometer. -Rheostat Resistor. -Trimmer Resistor. b- Non-Linear Resistors. In non-linear resistors, the value of resistance changes significantly with changes in voltage or current in an electrical circuit. This indicates the relationship between voltage and current is not proportional and it do not follow Ohm’s law. The resistor values change according to the temperature and voltage applied in the circuit. Non-linear resistors are mainly used in applications where resistance needs to be change based on the applied voltage or current. Non- linear resistors are mainly used in applications like voltage regulation or precise control. There are different types of Non-Linear Resistors: -Thermistors. -NTC (Negative Temperature Coefficient) Thermistor. -PTC (Positive Temperature Coefficient) Thermistor. -Varistors. -Photo Resistors.  Combination of Resistors. Resistors are used in various combinations. There are two methods of arranging the resistors in different combinations: 2   Resistors in Series Combination Two or more resistances are said to be connected in series when they are connected end to end and the same current flows through each of them in turn. In this case, the equivalent or the total resistance equals the sum of the number of individual resistances present in the series combination. 𝑛 𝑅𝑒𝑞 = ∑ 𝑅𝑛 = 𝑅1 + 𝑅2 + ⋯.. +𝑅𝑛 𝑖=1  Resistors in Parallel Combination Two or more resistances are said to be connected in parallel connected when they are connected between two points and each has a different current direction. The current is branched out and recombined as the branches intersect at a common point in such circuits. 𝑛 1 1 1 1 1 =∑ = + + 𝑅𝑒𝑞 𝑅𝑛 𝑅1 𝑅2 𝑅3 𝑖=1 Example. Give the equivalence of resistor in this circuit. Solution. Series 𝑅23 = 𝑅2 + 𝑅3 3  1 1 1 𝑅1 ∗ 𝑅23 parallel = + 𝑅𝑒𝑞 = 𝑅𝑒𝑞 𝑅1 𝑅23 𝑅1 +𝑅23  Value of resistor: The colored bands on a resistor can tell you everything you need to know about its value and tolerance, as long as you understand how to read them. The order in which the colors are arranged is very important, and each value of resistor has its own unique combination. To determine the value of a resistor using color codes, Identify the number of bands on the resistor: 4 bands: Two digits, a multiplier, and a 5 bands: Three digits, a multiplier, and a tolerance band. tolerance band. Example: Example: 100  ± 0.05% 162k ± 0.01% 4  25k ± 5% 210  ± 5% I.1.2. Capacitor: The primary use of a capacitor is to store electrostatic energy in an electric field and hence supply this energy whenever possible to the circuit. The SI unit of capasitor is Farad (F). The symbole of capasitors are.  Combination of Resistors.  Capacitors in Series Combination. When capacitors are connected in series, the total capacitance is less than any one of the series capacitors’ individual capacitances. If two or more capacitors are connected in series, the overall effect is that of a single (equivalent) capacitor having the sum total of the plate spacings of the individual capacitors. 1 1 1 1 = + +⋯.+ 𝐶𝑒𝑞 𝐶1 𝐶2 𝐶𝑁  Capacitors in Parallel Combination the total capacitance is the sum of the individual capacitors’ capacitances. If two or more capacitors are connected in parallel, the overall effect is that of a single equivalent capacitor having the sum total of the plate areas of the individual capacitors. 𝐶𝑒𝑞 = 𝐶1 + 𝐶2 + ⋯ + 𝐶𝑁 5  I.1.3. Inductor: An inductor is a passive electronic component that stores energy in the form of a magnetic field when electrical current flows through it. It typically consists of a coil of wire, often wrapped around a core made of magnetic material (like iron or ferrite), although air-core inductors exist as well. The symbol of inductor are : The property of the inductor that determines how much energy it can store in its magnetic field. It is measured in henries (H).  Applications of Inductors:  Energy Storage: Inductors temporarily store energy in their magnetic fields, especially in power supplies and converters.  Filtering: Inductors are used in filters to block certain frequencies while allowing others to pass (e.g., in radio tuning circuits or signal processing).  Transformers: Inductors with two or more coils can transfer energy from one circuit to another, often used in transformers. I.1.4. Diode. Is a passive electronic component that allows current to flow in only one direction. It has two terminals: anode (positive side) and cathode (negative side). Diodes are commonly used for rectification (converting AC to DC), protection, and signal modulation. The symbol of diode are:  Applications of Diodes:  Rectification: Converts AC to DC in power supplies.  Protection: Diodes can protect circuits from voltage spikes by allowing reverse current flow under certain conditions (e.g., flyback diodes in inductive loads).  Signal Processing: Used in radio receivers for signal demodulation.  LED Lighting: LEDs are used in displays, lighting, and indicators. 6  In summary, a diode controls the direction of current flow and is essential in power rectification, signal modulation, protection, and light-emitting applications. I.2. Active components. Active components are electronic components that require an external power source to operate and can control or amplify electrical signals. These components are essential in circuits because they can introduce gain, regulate voltage, or switch electrical currents I.2.1. Transistor. A transistor is a semiconductor device used to amplify or switch electronic signals and electrical power. It has three terminals: base (This is used to activate the transistor), collector (It is the positive lead of the transistor), and emitter (It is the negative lead of the transistor), and it operates by controlling the flow of current through its terminals. Transistors are foundational components in modern electronics and are used in: The first as an amplifier, turning a small electrical signal into a larger and more powerful one, the second is as a microscopic switch, allowing current to flow through only at specific times. Types of Transistors. There are mainly two types of transistors, based on how they are used in a circuit.  Bipolar Junction Transistor (BJT) The three terminals of BJT are the base, emitter and collector. A very small current flowing between the base and emitter can control a larger flow of current between the collector and emitter terminal. Furthermore, there are two types of BJT, and they include:  P-N-P Transistor: It is a type of BJT where one n-type material is introduced or placed between two p-type materials. In such a configuration, the device will control the flow of current. PNP transistor consists of 2 crystal diodes which are connected in series. The right side and left side of the diodes are known as the collector-base diode and emitter-base diode, respectively.  N-P-N Transistor: In this transistor, we will find one p-type material that is present between two n-type materials. N-P-N transistor is basically used to amplify weak signals to 7 strong signals. In an NPN transistor, the electrons move from the emitter to the collector region, resulting in the formation of current in the transistor. This transistor is widely used in the circuit. 8